The number of ministers setting up blind trusts in order to continue profiting from financial interests that could present a conflict with their government responsibilities has increased threefold under the coalition, official documents revealed today.

Sixteen ministers, including the energy secretary, Chris Huhne, the justice secretary, Ken Clarke, and the cabinet office minister, Francis Maude, have blind trusts in place, the official register of ministerial interests shows.

The register also includes many details about ministers' personal interests. David Cameron and the business secretary, Vince Cable, share a passion for bees and are both patrons of their local beekeepers' association. Theresa May is patron of the Pink Shoe Club, an exclusive networking club for women.

The register also reveals that the health secretary Andrew Lansley's wife, Sally Low, is managing director of Low Associates, a PR company that lists several major food and health-related companies as clients, including Mars, Kraft, General Foods and SmithKline Beecham. Low Associates also claims to do work for the government and the Conservative party.

Lansley has been seen as supportive of the food industry. Yesterday he said in an interview that "real opportunity exists to work together in partnership to make a commercial environment" that is conducive to improving people's health, "not by restricting choice but by extending it". An aide to Lansley insisted that Low had "meticulously" avoided any health-related contracts since her husband took the brief in opposition. "There is no conflict of interest," she said.

The deputy prime minister, Nick Clegg, will retire with both an MP and MEP pension, and Lord Green, the trade minister and former HSBC boss, will this year give his HSBC bonus – believed to be £3.6m – to a Christian charity to avoid any conflicts of interest.

Ministers are allowed to keep financial interests that could conflict with their ministerial briefs if they hand over their management to a trustee of a blind trust. They are allowed no further information about what investments are bought and sold through the trust and only receive updates of their profits and losses. The system is entirely legal. A cabinet office spokesman said: "If ministers have got financial assets and shares this is the fairest way for them to be handled so there is no perception of personal interest playing a part in their decisions in office."

Other ministers with such arrangements include the Northern Ireland secretary, Owen Patterson, the international development secretary, Andrew Mitchell, and the leader of the Lords, Lord Strathclyde.

Labour claimed it showed that the coalition was out of touch with ordinary people in the UK.

The system was heavily criticised when the register of ministerial interests was first published in March 2009.

The register is supposed to shed light on any potential conflicts of interest, but critics say that the blind trust arrangements damage that.

When the 2009 register was published, the Liberal Democrat Norman Baker, who is now a transport minister, was deeply critical of the system claiming that it lacked transparency, and called for the trustees to be named.

Jon Trickett, the shadow cabinet office minister, said the increase in the use of blind trusts confirmed people's perception of a government of privileged ministers. "They don't look, talk or behave like ordinary people. They are not representative of the wider population and ordinary people who struggle every day don't recognise this government."